Welded end closure means for rocket motors



Sept. 11, 1956 c. E. JOHNSON WELDED END CLOSURE MEANS FOR ROCKET MOTORS Filed Feb. 3, 1955 2 Sheets-Sheet 1 INVENTOR. Carl E. Johnson BY W *IM,

H/ ATTORNEYS Sept. 11, 1956 c. E. JOHNSON WELDED END CLOSURE MEANS FOR ROCKET MOTORS 2 Sheets-Sheet 2 Filed Feb. 3, 1953 Aww-\\\\\ I I Fig. 8

HVVENTUR. Carl E. Johnson H 5 ATTORNEYS WELDED END CLOSURE MEANS FOR ROCKET MOTORS Carl E. Johnson, Verona, Pa., assignor to Scaife Company,

Pittsburgh, Pa., a corporation of Pennsylvania Application February 3, 1953, Serial No. 334,917 Claims. (Cl. 6035.6)

This invention relates to a gas generating device. It relates more particularly to gas generating devices such as rockets, jet assist take-01f motors for airplanes, projectiles, war heads and land mines.

Rockets and jet assist take-off motors, for example, comprise a metal container open at one end, a propellant charge of ignitible gas generating material in the container, a nozzle at the rear end of the device through which the gas is discharged and a metal end closure secured to the rear end of the device for retaining the gas generating charge in the container and for providing the nozzle. Prior to my invention, the end closures which have been used were cumbersome, heavy, expensive to manufacture and difficult to assemble and secure to the container. These end closures take the form of bolted flanged connections, screwed, crimped or riveted assemblies, or snap ring closures usually consisting of the snap ring and a confining member with the necessary bolts or screws to hold the parts in place.

In accordance with the present invention, I depart from the usual construction for securing the end closure to the container in which the charge of ignitible gas generating material is enclosed. I have found that the end closure can be welded to the container without igniting the gas generating material provided the end closure is made in the form hereinafter more particularly described and provided that other suitable precautions are taken when necessary. Generally speaking, the end closure has a part extending away from the charge of gas generating material. That part of the end closure is welded to the container at such a distance from the charge that during welding, the temperature of the container adjacent the end of the charge nearest the end closure is less than the ignition temperature of the charge. Preferably the end closure is generally cup-shaped having a bottom portion and a side wall and is placed in the container with its bottom portion adjacent the charge and its side wall extending away from the charge andlying adjacent the container. The side wall of the end closure is then welded to the container at a point or points far enough away from the charge so that the charge is not ignited during welding. Preferably the end closure is welded to the container at a point adjacent the lip of the cup-shaped end closure.

The invention provides a relatively inexpensive method for securing the end closure to the container which can be performed rapidly and relatively cheaply as compared with prior known methods.

In the accompanying drawings which illustrate several embodiments of my invention- Figure 1 is a longitudinal section through a jet assist take-oft" motor as adapted to be secured to an airplane and operated to assist the plane in taking off from the ground, certain parts of the motor being omitted;

Figure 2 is a section taken on the line II--II of Figure 1;

Figure 3 is a partial longitudinal section similar to Figure 1 but illustrating a difierent type of weld;

Figure 4 is a partial longitudinal section similar to Fig 'pellant discharges.

ure 1 but illustrating a still dilferent type of weld, the nozzle portion of the end closure being separable from the remaining portion of the end closure;

Figure 5 is a partial longitudinal section illustrating the welding step employed in performing the weld shown in Figure 4;

Figures 6, 7 and 8 are longitudinal sections through the etal container or metal body and associated parts of the motor, illustrating different stages of the method employed in assembling the motor parts and gas generating material;

Figure 9 is a partial longitudinal section generally similar to Figures 1, 3 and 4 but disclosing an embodiment in which the nozzle end of the container is of reduced diameter and in which the propellant charge is cast in place in the container instead of being preformed; and

Figure 10 is a longitudinal section through an explosive mine.

Referring-more particularly to the accompanying drawing-s and for the present to Figures 1 and 2,.the jet assist take-off motor there illustrated comprises a steel container or chamber body 2, which is of generally cylndrical crosssection' and is closed at its forward end by a head 3. The container is provided with brackets 4 for securing it to an air craft and with a support ring 5 used for vertical storage and handling. A propellant charge 6, which is an ignitible gas generating material, is located within the container and is provided at its center with a longitudinally extending hole 7, which in the embodiment illustrated is star-shaped but which may be of any other suitable cross-section. The propellant charge comprises a fuel and an oxidizer, the fuel for example being a mixture of asphalt and paraffine base motor oil and the oxidizer being potassium perchlorate.

A metal end closure, indicated generally by reference numeral 8, is inserted into the open end 9 of the container and is secured by welding 10 to the container. A body 11 of heat insulating material, as for example asbestos and a suitable resilient binder molded to proper shape, is interposed between the propellant 6 and the end closure 8. The heat insulating body 11 shields the propellant from heat generated in making the welds 10 and, furthermore, acts as a take-up for variations in metal parts manufacture or in the amount of the propellant charge.

The metal end closure 8, is generally cup-shaped and comprises a bottom portion 14, a side wall 15, and a centrally disposed annular nozzle portion 17. A preformed body 18 of carbon or other refractory material is pressed into the nozzle portion 17 before the end closure 8 is welded to the container 2, the body 18 and the heat insulating body 11 providing a venturi-shaped nozzle opening through which gas generated upon igniting the pro- The weld 10 is made by penetration arc welding and during the welding operation cooling fluid is supplied from nozzles 19 to the parts adjacent the weld. During the welding, a cover 20 is placed over the nozzle 17 to further protect the propellant. The motor includes an igniter assembly for igniting the propellant charge and safety pressure release for preventing excessive pressures within the motor, those parts not being shown since they are not necessary to an understanding of the invention.

In the embodiment illustrated in Figure 3, parts corresponding to those shown in Figure 1 are designated by the,

meter of the container.

gas generating material.

resistance welding operation. The nozzle portion 17b is separable from the remaining portion of the end closure 3b and for this purpose is provided with threads 22 which cooperate with corresponding threads 23 on the other part of the "end closure. In Figure 5 the rollers of the welding machine are designated by reference numeral 24. The nozzle portion 17b of the end closure is not installed until after the welding operation in order to provide sufficient space for the welding rollers. The nozzle portion is then threaded into the end closure.

Referring to Figures 6, 7 and 8, which illustrate diifcrent stages in completing the rocket motor, the container 2 is placed 'on its closed end with the open end extending upwardly and then the preformed charge 6 of propellant is inserted into the container. Thereafter, asshown in Figure 7, a prefolrned body 11 of heat insulating material is applied to the top of the propellant. The cup-shaped metal end closure 8 is then inserted into the open end of the container against the insulating body 11, a protective cover 20 is placed over the nozzle 17, and the end closure is welded to the container at it).

As illustrated in Figures 6-8, the propellant charge 6 is preformed and in order to insert it into the container it must be of somewhat less diameter than the inside diam- Where, however, the propellant is introduced into the container in liquid form and thereafter cured or otherwise allowed to solidify, the end 25 of the'container 2 can be made of smaller diameter diameter as is illustrated in Figure 9, allowing end closure 80 to be likewise smaller to reduce its Weight, which is important in roclce ry.

The explosive mine illustrated in Figure 10 comprises a steel container 2'7, an end closure 23 having a bottom portion 29 and a side wall 30, the side wall extending away cooling the metal parts adjacent the weld in order to maintain the parts below the ignition temperature of the The parts can be cooled by any suitable means, such for example as employing a blast of cool air or other fluid, or by placing a chill, such as a fluid cooled ring, around the end of the container adjacent the weld.

In all of the embodiments, the welding is carried out at such a distance from the body of ignitible material that during welding thetemperature of the container at the points corresponding to the point designated by reference numeral 36 in Figure l is less than the ignition temperature of the ignitible material. It would not occur to one skilled in the art that a welding operation could be employed to secure a metal end closure to a metal container confining a readily ignitible charge of gas generating material without danger of igniting the charge. In accordance with my invention, I can secure the metal parts together without igniting the charge by employing an end 4 closure of suitable configuration as described, and, if necessary, cooling the parts adjacent the weld.

The invention is not limited to the preferred embodiment but may be otherwise embodied or practiced within the scope of the following claims.

I claim:

1. A gas generating device, comprising a metal container open at one end, a charge of ignitible gas generating materialin the container, ametal end closure in the open end of said container for retaining said charge in the container, a body of heat insulating-material in said container between said end closure-andsaid charge, said end closure having a part extending away from said charge and welded to said container'at such a distance from said charge that during welding thetempera-ture of the'container adjacent the end of said charge nearest said end closure is less than the ignition temperature of said charge.

2. A gas generating device, comprising a metal container open at one end, a charge of ignitible gas generating material in the container, a metal end closure in the open end of said container cfor retaining said charge in the container, said end closure being generally cup-shaped with its bottom portion adjacent said charge and its side wall extending away from said charge and lying adjacent said container, the side wall of said end closure being welded to'said container at such a distance from said charge that during welding the temperature of the container adjacent the end of said charge nearest said end closure isless than the ignition temperature of said charge.

3. A gas generating device according to claim 2, wherein a body of heat insulating material is located between said end closure and said charge.

4. A gas generating'device, comprising a metal container open 'at one end, a charge of ignitible gas generating material in the container, a metal end closure in the open end of said container 'for retaining said charge in the container, said end closure being generally cup-shaped with its bottom portion adjacent said charge and its side wall extending away from said charge and lying adjacent said container, said end closure being welded to said container adjacent the edge ofsaid end closure. 7

5. A gas 'generatingdevice,comprising a metal container 'open at one end, a charge of ignitible gas generating material in the container, 21 metal end closure in the open end of said container for retaining said charge in the container, said "end closure being generally cup-shaped -with*i-ts bottomportion adjacent said charge and its side wallextending awayfrom said charge and lying adjacent said container, said end closure having an inner annular nozzle portion, the side wall of said end closure being weldedjto said container atsuch a distance from said chargethatduring welding the temperature of the container adjacent the end of said charge nearest said end closure is less than the ignition temperature of said charge.

References. Cited in the file of this patent UNITED STATES PATENT S 2,481,059 -Afri cano Sept. 6, 1949 

